Ischemic heart disease in blacks is characterized by microvascular dysfunction, left ventricular hypertrophy, increased sensitivity to catecholamines, a predominance of salt-sensitive hypertension, and relatively worse outcome for extent of macrovascular disease. Preliminary studies have demonstrated profound loss of nitric oxide action in the coronary vasculature of a group of hypertensive black patients without epicardial disease. As a central hyperthesis, we have proposed that nitric oxide insufficiency plays a pathophysiologic role in the black vascular diathesis. This project aims to compare nitric oxide dependent vasomotor function in black and white subjects using a non-invasive, brachial ultrasound technique.